This invention relates generally to the testing and/or servicing of circuit boards, and is particularly directed to an extender board arrangement for allowing testing/troubleshooting of a circuit board while electrically connected, yet physically removed from its in-service position.
Circuit boards are frequently installed in an equipment rack, wherein a plurality of such circuit boards are maintained in a parallel, closely spaced arrangement. The leading edge of the circuit board as it is installed in the equipment rack is typically provided with a plurality of spaced terminals or contacts for insertion in and electrical coupling to a fixed connector in the equipment rack. Adjacent edges of the circuit board may also be provided with spaced terminals, or contacts, along the length thereof for electrical coupling to other connectors within the equipment rack. The circuit board may take on various forms, with the printed circuit (PC) and wired circuit boards being two of the more common types of circuit boards. The former generally includes etched or plated circuits on a substrate, while the latter includes insulated wires attached to the substrate in a predetermined pattern. The substrate, generally in the form of a planar sheet, generally provides mechanical support and electrical insulation, but also sometimes performs a useful electrical function.
Sometimes it is necessary to test or service a circuit board by removing it from the equipment rack and coupling it to the circuitry therein by means of an extender board, or card. The extender board is typically inserted in the connectors in which the circuit board is installed and provides electrical leads to its outer edge to which the circuit board is connected for testing/troubleshooting. The extender board thus provides a plurality of conductive paths between the fixed connector mounted in the equipment rack and the leading edge of the circuit board following its removal from the equipment rack. The removed circuit board is thus coupled to the circuitry with which it operates in the equipment rack, while removed from the equipment rack, to allow for replacement and/or repair of circuit elements on the circuit board. An example of such an extender board for coupling leading edge terminals on a circuit board to a connector in an equipment rack following removal of the circuit board from the equipment rack can be found in U.S. Pat. No. 2,951,185 to Buck.
Extender boards of the type discussed above provide an electrical connection to and limited support for the circuit board during testing. The circuit board is first removed from its installed position and the extender board is inserted in the same position in place of the circuit board. Inner and outer edges of the extender board are provided with a plurality of spaced terminals or an elongated connector to permit the extender board to be electrically coupled to circuitry in the equipment rack on its inner edge and to the removed circuit board on its outer edge.
Another type of circuit board has terminals on both its front and back edges. This type of circuit board is mounted in a cabinet with the terminals on its rear edge connecting to the contact elements in the inside of the cabinet, with its front edge terminals inserted into a flexible type connector which is electrically connected to appropriate contact elements in the cabinet. In-service testing is performed with the previously described extender board used with single edge boards. The back edge of the circuit board is inserted into the front edge connector of the extender board, while the terminals on the back edge connector of the extender board are connected to contact elements in the cabinet. The front edge of the circuit board is connected to the existing flexible connector, if that connector is long enough, or an extension connector is used to reach terminals on the circuit board's front edge.
With the increasing use of circuit boards having contacts on two or more adjacent edges, "in place" testing of the circuit board has become increasingly difficult. Such testing/troubleshooting of circuit boards has been further complicated by the closer spacing of adjacent circuit boards brought about by more restrictive space constraints as well as by the use of dual sided and multi-layered circuit boards. Testing of these latter types of circuit board generally requires a separate test module for providing selective inputs to the circuit board and reading designated outputs therefrom. In addition, during testing of the removed circuit board it is attached to the extender board generally by electrical connections only and is thus only loosely supported in an unstable manner.
The present invention eliminates the need for such complicated and expensive circuit board test equipment by allowing the testing of dual sided circuit boards having terminals on two or more adjacent edges in their operating environment. The present invention contemplates the use of an extender board which is inserted in the in-service position of the circuit board and provides conductive paths to each of the multiple edge positioned terminals of the circuit board after removal from its equipment rack and attachment and electrical coupling to the extender board.